Leveling head



E. w. ARMs 1,779,080

LEVELING HEAD Oct. 21, 1930.

Filed Dec:` 22, 1927 Patented Oct. 2l, 1930 on TROY, Nnw Yonx,

yiii-lumai) W. ARMS,

' LEvnLINe HEAD l Application `filled December 'This invention relates; to leveling heads "for surveying instruinents and resides in certain Avdetails of construction conduciveto ease of manufacture and repair and producinga better instrument. l K y. e g

nThey objectof the invention isto take ull i advantage, of certain highly developedinanuyill) facturing 'processes of recent origin, and to avail of certain new `inaterial's which could not otherwise he successfully used vin this art.

` :The inventionwill now rhe described with reference to the accompanying drawing which illustrates by way: Vinghead for a transit.l y

In the drawing# Fig. l isa planview.

Fig. 2 is a vertical axial section.'

ofV exainple af'level .The head on which the `transitlfifaiine (not l formed integrally with tapered spindle r7, which is relieved shoulder K Thev spindle n p y quill 1l ground accurately tofft).

.at its VVupper .end shoulder' Qfin euch i ror'tlilg relation ae to prevent seizing or looseness of the taper Ahearing p upper end an outwardly project-ing langelQ. to which is connected the graduated linib Vv(,-nnt

, The `quill 11 has atv its ,ShOWnl Y Connectedto flange 12' by screws'7 one, of

which appears at 13,is an annular collar lll which receivestlie Alinnb'clainp .L5 Aand thev` A y Y MlGOfusual construction. i '.'Thelinib clainp l5 'isr tightenedby. a screw;

:leveling head clamp v whose headappears at 17,1a`nd when' ree rpor, tatesfon vcollarlll onfwhich -it iefretainedfhy nut 518. Thel clamp .Vineniher l5l ent'eisloetween theiisual opposed adj usting screw and ,spring plunger 'carried by thetransitv 'raine (not Shown).y 1

` t The leveling lie'adclainp "lisitightened a clamp screwp-19 whoseiheadj appearsjat'l and when. unclampedpermi-ts the. rotation ofv the limb.aiidzquillfll:relatively thereto." i The leveling head .clamp 16': enters hetw'eenl Vthe usual adjusting screwV 22 springplunger carried lon theksipider of "thefleve'ling head vwliieh i'syettohefdescribedf.

at 8 and whichhas a thrust 7 turna in a'pftaperedfsle'eve'or andisup- 22, i927. serali No. v241,998.

, `The parts'r so described conior'inv 'to known practice.

The quill*v 11l 'fingen the upper lend of shell26 and performing a Jfunction siinilar'to'thatof shoulder y has va shouldereland lieved at" 25. The quillis rotatablefin a ta'- i 'f Ipered hearing. shell v"26 theshoulder Qllrest- 55;

9 hv preventing seizingl or shaking. ofy the v'quill in the sleeveQG.

'integral with spider 27 ofthe leveling hea-d `but is:removably"supported'therein in sii-cli away that the two are rigidly connected when in use VThis is accomplished bya' close cylin- 'dricalY slipl fit'L 28 and annular flangev 29,' the Contrary to prior practice, shell Qti'is not flange seating on the spiderV and being heldv 5 againetrotation by a pin The flange 29 ralso serves to retain `clamp 16 onv collar-14.

"is usual, 'the' varins 'being ofslieletn formation tov reduce weighty as indicated Ein Fig.J A1.

in'g'to receive andfclosely co'iiinea flanged a 'levelingscrew 33 withdinurledfwheel 34 and swiveled .thrust `head' .35.V Each arm p sertedthiniblesBQlp l Wported 'by screws 33' Yon .annular basiefplate hThe `spiderA ,f2/Tis preferably cruciforimas internally threadedl thiinble 32 whiichcarrie'sv The wholeleveling head VEach arrn is formed at its end with anf'o'pen-l slotted Aas shownat 36 and capstanscrews f "37 serve to clamp the armeuponthe in-k fflhe lparts varef'he'ldi in vengagement. Vwith bas'efplate 38 v and allowed universal 'lateral rand angularinotion .ofreasonahle plate f 41 :which `engagesy beneath fplatef38" and has anannular vsocket 42of spherical y contour projecting upward tl'irioughl thecentral opening of plateBS.`V a

In this socket-engages la nut 43 of spherical contour which'is threaded onto the lower :end of shell26, andseats against 'shoulder "In this way,.yvhatina'y vbe described i generically as aV yuniversal y joint, isf formed. The'nut isflocked in positionv v hy y a cupda; 'tripod' head onf'ther support" Iio.t{shown) Y shaped check nut-45 screwed into thepp'rojec'ting" lower end'fofiiutl 4,3 and" seating f against a shoulder formed on shellf26 near'l the lower end thereof. Nut l5 has an eye 46 for the connection of the plumb line.

The spindle 7, quill 11 and shell 26 are held in assembled relation by machine screw 47 threaded into the end of spindle 7, and washer 48 through which the screw passes, the Washer seating against the end of shell 26 within nut 45.

The screw 22 and spring plunger 23 are supported on brackets t9-integral with spider 27. The screw 22 is threaded in a barrel or nut 51, whicn is threaded into one bracket 49 and locked by clamp screw 52 against turning. The plunger 23 is guided in sleeve 53 which houses the spring (not shown). Sleeve 53 is threaded' into the other bracket 49.

The described construction of the parts is such that the thrust of the leveling screws holds all parts in assembled relation. At the same time internal strains set up in the spider by the thrust of leveling screws are not transmitted to the bearing shell 26, or at any rate are not transmitted in any appreciable degree. The shell 26 being a solid of revolution with reference to its longitudinal axis is symmetrical and symmetrically stressed and stressed longitudinally only. Hence distortion and strains are minimized and rendered neutral so far as accuracy of the spindle bearing is concerned.

The widest range of choice of materials is offered, and it becomes possible to use a die casting for the spider 27 with a marked economy in manufacture resulting from the elimination of numerous machining operations.

The ease and economy of making repairs and replacements is, from the users standpoint, probably the most valuable feature of the invention. The spindle bearing is the most important and one of the most expensive parts of the instrument. In prior constructions injury to the spider, and in some cases very minor injuries, required the replacement of the whole part including the bearing. vModern manufacturing methods make possible the production of bearing shells 26 on the basis of strict interchangeability. Thus the spider or the shell may be replaced individually in a leveling head embodying the present invention, and this replacement can be made in the field, a practice heretofore considered beyond the range of practicability.

What is claimed is,- Y l. A leveling head comprising in combi.-

nation, a base plate; a spider having a central opening; a plurality of leveling screws reacting adjustably between said base plate Y andspider; a main spindle bearing member adapted to guide in rotary movements the spindle structure of a geometrical instrument, said bearing member being seated in said opening in the spider land having means to support said spider against stress exerted by said leveling screws; and a universal joint connecting said bearing member and base plate.

2. A leveling head comprising in combination, a base plate; a bearing shell adapted to guide in rotary movements the spindle structure of a geometrical instrument, said shell being symmetrical with reference to the axis of its bearing surface and-having a thrust shoulder; a universal joint connecting said shell and base plate; a plurality of adjustable leveling screws; and a member in .thrust engagement with said shoulder and adjusted by Vsaid screws.

3. A leveling head comprising in combination, a base plate; a bearing shell which is annular solid of revolution about the bearing axis, said shell being adapted to guide in rotary movements the spindle structure of a geometrical instrument, and having an annular thrust shoulder; a universal joint connecting said shell and base plate; a plurality of adjustable leveling screws; and a spider separate from said bearing shell adjusted by said screws and in thrustengagement with the shoulder on said bearing shell to stress the latter in tension in the direction of its axis.

4l. A leveling head structure comprising in combination, a base plate; a spider formed with openings to receive and confine thimbles for leveling screws and a central opening to receive a. main spindle bearing; leveling screw units each including a thimble seated -in a corresponding one of said openings,said

units reacting adjustably between said base and spider; a main spindle bearing member adapted to guide in rotary movements the spindle structure of a geometrical instrument, said member being seated in said central opening and provided with means to support said spider against the stress exerted by said leveling screw units; .and a universal joint connecting said bearing and base plate adapted to permit universal angular motion of said bearing and spider relatively to said base plate.

5. In a leveling head, the combination of an annular base plate; a thrust plate laterally shiftable relatively to said base plate an and having a spherical bea-ring; a spider; a plurality 'of leveling screws threaded in said spider and enga-ging the upper side of said base plate; and a spindle bearing member adapted to guide in rotary movements the spindle structure of a geometrical instrument, said member being distinct from said spider and engaging the spiderl and said spherical bearing, whereby the spindle bearing member is stressed inV simple tension in the direction of its axis.

6. A leveling head of that known type which includes a base; a spider supportedon the base by means of leveling screws;and a spindle bearing member, which is adapted to guide in rotary movements the spindle structure of a geometrical instrument, and which forms a connection between the base and the spider; characterized by the fact that said bearing member isa separate piece from the spider and so related to the spider and base that the bearingmember is stressed in simple axial tension in all positions of the device.

m 7 A leveling head comprising in combination, a base plate; a spider having a central opening; a plurality Vof leveling screws reacting adjustably between said base plate and spider; a main spindle bearing member adapted to guide in rotary movements they spindle structure of a geometrical instru# j ment, said bearing member being seated in said opening in the spider, rigidly confined thereby, and having means to support said spideragainst stress exerted by said leveling screws; and a universal oint connecting said bearing member and base plate. j

8. A leveling head comprising in combina# tion, a base plate; a bearing shell adapted to guide in rotary movements the spindle structure of a geometrical instrument, said shell being symmetrical with reference to the axis of its bearing surface and havinga thrust shoulder; a universal joint connecting said 3o shell and base plate; a plurality of adjustable leveling screws; and a member encirc` ling and rigidly confining said bearing ,shell f and in thrust engagement with said shoulder, j said member being adjustable by said screws.

9. A leveling head comprising in combina-- tion, a base plate; a bearing shell which is an annular solidof revolution about the bearing axis, said shell being adapted to guide in Vrotary movements a spindle structure of a 40 geometrical instrument'and having an annular thrust shoulder; a universal joint connecting said shell and base plate; a plurality of adjustable leveling screws; and a spider separate from said bearing shell and adjusted 45 by said'screws, said spidery encircling and rigidly confining lsaid bearing shell 'and Ventering into thrust engagement with the shoulder'on said bearing shell to stress the latter in tension in the direction of itsaxis. In testimony' whereof I have signed my name to this specification. s

EDWARD W. ARMS. 

